Current optical mass storage devices record data on a small disk. The disk spins at a controlled rate on a spindle. A read/write head is held close to the surface of the disk. The head moves radially to scan a given ring-shaped track on which data is stored.
Using current optical mass storage devices, data transfer is delayed by: (1) the time required to find the correct location of the data on the disk, and (2) the time required for the disk to rotate while the data is transferred. When a moving disk is used in an optical mass storage device, the location of the beginning of the data is randomly delayed by the current position of the disk in relation to the head. If the beginning of the data has just passed the head, the wait is maximized to the time it takes for the disk to make nearly an entire revolution. In cases where the data is chopped up into separate pieces located at random on the disk surface, these delays can add up to a significant amount of the total read/write time. This problem is further aggravated by the delay caused by the time required for a spinning disk to reach operating speed.
When a rotating disk is used as a recording medium, data reading and writing can only be performed at the speed at which the data passes in front of the fixed head. Even when high speed hard disks are used, the data rate is far slower than the maximum rate at which the electronic circuits in the attached computer could function. As new ultra-high-speed devices such as Very High Speed Integrated Circuit (VHSIC) come into use, the disparity between the electronic devices and the mechanical mass storage devices is going to widen dramatically. This is the primary limitation of any data storage device which requires a moving medium.